Along an assembly line, diapers and various types of other absorbent articles may be assembled by adding components to and otherwise modifying an advancing, continuous web of material. For example, in some processes, advancing webs of material are combined with other advancing webs of material. In other examples, individual components created from advancing webs of material are combined with advancing webs of material, which in turn, are then combined with other advancing webs of material. Webs of material and component parts used to manufacture diapers may include: backsheets, topsheets, absorbent cores, front and/or back ears, fastener components, and various types of elastic webs and components such as leg elastics, barrier leg cuff elastics, and waist elastics. Once the desired component parts are assembled, the advancing web(s) and component parts are subjected to a final knife cut to separate the web(s) into discrete diapers or other absorbent articles. The discrete diapers or absorbent articles may also then be folded and packaged.
For quality control purposes, absorbent article converting lines may utilize various types of sensor technology to inspect the webs and discrete components added to the webs along the converting line as absorbent articles are constructed. Example sensor technology may include vision systems, photoelectric sensors, proximity sensors, laser or sonic distance detectors, and the like. Product inspection data from the sensors may be communicated to a controller in various ways. In turn, the controller may be programmed to receive product inspection data, and in turn, make adjustments to manufacturing process. In some instances, the controller may reject defective diapers based on the product inspection data after the final knife cut at the end of the converting line.
In addition, absorbent article converting lines may utilize various types of process sensor technology to monitor the performance of various types of assembly equipment used on the converting line. Example process sensor technology may include speed sensors, linear or radial position sensors, temperature, pressure or vacuum sensors, vision systems, proximity sensors, and the like. Process data from the process sensors may be communicated to a controller in various ways. In turn, the controller may be programmed to receive process data, and in turn, make adjustments to manufacturing process and/or communicate potential problems associated with assembly equipment to converting line operators. In some instances, based on the process data, the controller may automatically shutdown the converting line.
In further efforts to improve and control quality of manufactured absorbent articles, manufacturers may conduct extensive product testing and/or consumer research on various aspects of absorbent articles. Product performance data obtained from such product testing, in turn, may be used as a tool by manufacturers to make future converting equipment and/or processing adjustments.
Consequently, it would be beneficial to provide a system that is capable of precisely correlating product inspection data, process data, and product performance data with each other and/or with corresponding absorbent articles from where such data is obtained. However, there are challenges associated with precise correlation of such data. For example, the controller may not be able to correlate product inspection data with exact locations in the web and corresponding diapers with a very large degree of accuracy due to slow sensor response, data transportation delays and control loop execution times. For example, the sensor and control technologies may work asynchronously of each other, thus creating control system accuracy challenges, which may be exacerbated at the high speed production rates of some absorbent article processes.
Further, product inspection data and process data is traditionally recorded and correlated to the time at which the data was acquired. As such, an event that happens upstream in the process and causes a second event downstream would be recorded with different time-stamps and cannot be easily correlated without extensive data processing and detailed knowledge of the process conditions at the time.
Finally, when products are inspected away from the manufacturing process, such as in a quality assurance lab, the data may be stored with a time-stamp generated at the moment that the data is posted to the database, rather than the time-stamp at which the product was produced. The same time-stamp issue is present for product performance data, which is sometimes obtained at a significantly different time than the time at which the product was produced. For these same reasons, the controller may not be able to precisely correlate obtained process data and/or product performance data with inspection data and/or manufactured absorbent articles.